When viewed from orbit, Giordano Bruno is at the center of a symmetrical ray system of ejecta that has a higher albedo than the surrounding surface.

[2] Five witnesses from Canterbury reported to the abbey's chronicler, Gervase, that shortly after sunset on 18 June 1178, they saw "the upper horn [of the moon] split in two".

Furthermore, Gervase writes: From the midpoint of the division a flaming torch sprang up, spewing out, over a considerable distance, fire, hot coals and sparks.

[4] Modern theories predict that a (conjectural) asteroid or comet impact on the Moon would create a plume of ejecta rising up from the surface, which is consistent with the monks' description.

[4] Because micrometeorites constantly rain down, they kick up enough dust to quickly (in geological terms) erode a ray system.

[4] The impact creating the 22-km-wide crater would have kicked up 10 million tonnes (10 billion kilograms) of debris, triggering a week-long, blizzard-like meteor storm on Earth – yet no accounts of such a noteworthy storm of unprecedented intensity are found in any known historical records, including the European, Chinese, Arabic, Japanese and Korean astronomical archives.

An alternative theory holds that the monks just happened to be in the right place at the right time to see an exploding meteor coming at them and aligned with the Moon.